NFL Network's Ian Rapoport reports Patriots LB Dane Fletcher sustained a torn left ACL in Thursday's preseason opener.Fletcher drew the start in the middle with Brandon Spikes sitting out. Following the injury, rookie Dont'a Hightower moved from the strong side to Fletcher's spot. The injury will increase the responsibilities of veteran Bobby Carpenter, who was signed for depth and versatility. Fletcher was expected to be Spikes' primary backup this season.